Cellulose Nanofiber-Based Nanocomposite Films with Efficient Electromagnetic Interference Shielding and Fire-Resistant Performance.

Cellulose nanofiber (CNF) has been widely used as a flexible and lightweight polymer matrix for electromagnetic shielding and thermally conductive composite films because of its excellent mechanical strength, environmental performance, and low cost. However, the lack of flame retardancy seriously hinders its further application. Herein, renewable and biomass-sourced l-arginine (AR) was used to surface-modify ammonium polyphosphate (APP) and an environmentally friendly biobased flame retardant was synthesized by the coordination of zinc sulfate heptahydrate (ZnSO4·7H2O), which was named AAZ. AAZ was deposited on the surface of CNF by electrostatic adsorption and Zn2+ complexation. The biobased compatibilizer Triton X-100 was employed to assist the exfoliation of graphene nanoplatelets (GNPs) and their dispersion in the CNF matrix. Due to the formation of a dense lamellar layer resembling a shell structure, the CNF/GNPs composite films with a tensile strength of 52 MPa were obtained via vacuum-assisted filtration. Because the phosphorus-containing group produces a protective layer of PxOy compound and promotes the formation of a carbon layer by CNF and the combustion releases ammonia gas, the fire-resistant performance of the composite films was greatly improved. Compared with the pure CNF film, the composite film exhibits 33% reduction in PHRR value and 40% reduction in THR. In addition, the CNF/GNPs composite film with 20 wt % GNPs possessed high conductivity (2079.2 S/m) and electromagnetic interference (EMI) shielding effectiveness (37 dB). The ultrathin CNF/GNPs composite films have excellent potential for use as efficient flame retardant and EMI shielding materials.

Atomic Ruthenium-Promoted Cadmium Sulfide for Photocatalytic Production of Amino Acids from Biomass Derivatives.

Amino acids are the building blocks of proteins and are widely used as important ingredients for other nitrogen-containing molecules. Here, we report the sustainable production of amino acids from biomass-derived hydroxy acids with high activity under visible-light irradiation and mild conditions, using atomic ruthenium-promoted cadmium sulfide (Ru1/CdS). On a metal basis, the optimized Ru1/CdS exhibits a maximal alanine formation rate of 26.0 molAla ⋅ gRu -1 ⋅ h-1, which is 1.7 times and more than two orders of magnitude higher than that of its nanoparticle counterpart and the conventional thermocatalytic process, respectively. Integrated spectroscopic analysis and density functional theory calculations attribute the high performance of Ru1/CdS to the facilitated charge separation and O-H bond dissociation of the α-hydroxy group, here of lactic acid. The operando nuclear magnetic resonance further infers a unique "double activation" mechanism of both the CH-OH and CH3-CH-OH structures in lactic acid, which significantly accelerates its photocatalytic amination toward alanine.

High-Rate CO2 Electrolysis to Formic Acid over a Wide Potential Window: An Electrocatalyst Comprised of Indium Nanoparticles on Chitosan-Derived Graphene.

Realizing industrial-scale production of HCOOH from the CO2 reduction reaction (CO2 RR) is very important, but the current density as well as the electrochemical potential window are still limited to date. Herein, we achieved this by integration of chemical adsorption and electrocatalytic capabilities for the CO2 RR via anchoring In nanoparticles (NPs) on biomass-derived substrates to create In/X-C (X=N, P, B) bifunctional active centers. The In NPs/chitosan-derived N-doped defective graphene (In/N-dG) catalyst had outstanding performance for the CO2 RR with a nearly 100 % Faradaic efficiency (FE) of HCOOH across a wide potential window. Particularly, at 1.2 A ⋅ cm-2 high current density, the FE of HCOOH was as high as 96.0 %, and the reduction potential was as low as -1.17 V vs RHE. When using a membrane electrode assembly (MEA), a pure HCOOH solution could be obtained at the cathode without further separation and purification. The FE of HCOOH was still up to 93.3 % at 0.52 A ⋅ cm-2 , and the HCOOH production rate could reach 9.051 mmol ⋅ h-1 ⋅ cm-2 . Our results suggested that the defects and multilayer structure in In/N-dG could not only enhance CO2 chemical adsorption capability, but also trigger the formation of an electron-rich catalytic environment around In sites to promote the generation of HCOOH.

In situ construction of 3D NiMo bimetallic catalysts anchored on dendritic mesoporous silica for the upgrading of biomass derivatives.

Reasonable construction of bi-function catalysts with well dispersed hydrogenation active sites and acidic sites are crucial for the hydrodeoxygenation (HDO) of biomass-derived compounds but still a huge challenge. Herein, a 3D Mo functionalized Ni-based bimetallic embedded catalyst with fine metal nanoparticles size (<6 nm) was prepared for the first time using dendritic mesoporous silica as a sacrificial template by one-pot hydrothermal synthesis and adopted in the HDO process of vanillin (VAN) upgrade to 2-methoxy-4-methylphenol (MMP). The characterization results illustrated that Mo species regulated the acidity of the catalyst and promoted the formation of Ni-Mo alloy sites. Density functional theory (DFT) calculations further unveiled that Ni-Mo alloy sites promoted the activation and dissociation of CO bond in VAN, enhanced the ability of protonation hydrogenolysis. Benefitting from the synergistic effect of the highly uniformly dispersed hydrogenation metal sites and acidic sites, nearly 100% yield of MMP could obtained over the designed catalyst under mild conditions (130 °C, 1.5 MPa H2, 3 h, 10 wt% catalyst dosage). Additionally, the NiMo0.1@MSN catalyst displayed robust activity for no less than 8 recycles and excellent universality for the HDO of a variety of lignin derivatives and biomass platform molecules, which provide a feasible strategy for the construction of 3D confined catalysts for the high-efficiency HDO of biomass derivatives.

l-Lysine Stabilized FeNi Nanoparticles for the Catalytic Reduction of Biomass-Derived Substrates in Water Using Magnetic Induction.

The reduction of biomass-derived compounds gives access to valuable chemicals from renewable sources, circumventing the use of fossil feedstocks. Herein, we describe the use of iron-nickel magnetic nanoparticles for the reduction of biomass model compounds in aqueous media under magnetic induction. Nanoparticles with a hydrophobic ligand (FeNi3 -PA, PA=palmitic acid) have been employed successfully, and their catalytic performance is intended to improve by ligand exchange with lysine (FeNi3 -Lys and FeNi3 @Ni-Lys NPs) to enhance water dispersibility. All three catalysts have been used to hydrogenate 5-hydroxymethylfurfural into 2,5-bis(hydroxymethyl)furan with complete selectivity and almost quantitative yields, using 3 bar of H2 and a magnetic field of 65 mT in water. These catalysts have been recycled up to 10 times maintaining high conversions. Under the same conditions, levulinic acid has been hydrogenated to γ-valerolactone, and 4'-hydroxyacetophenone hydrodeoxygenated to 4-ethylphenol, with conversions up to 70 % using FeNi3 -Lys, and selectivities above 85 % in both cases. This promising catalytic system improves biomass reduction sustainability by avoiding noble metals and expensive ligands, increasing energy efficiency via magnetic induction heating, using low H2 pressure, and proving good reusability while working in an aqueous medium.

Highly Selective Transformation of Biomass Derivatives to Valuable Chemicals by Single-Atom Photocatalyst Ni/TiO2.

Selective CC cleavage of the biomass derivative glycerol under mild conditions is recognized as a promising yet challenging synthesis route to produce value-added chemicals. Here, a highly selective catalyst for the transformation of glycerol to the high-value product glycolaldehyde is presented, which is composed of nickel single atoms confined to the surface of titanium dioxide. Driven by light, the catalyst operates under ambient conditions using air as a green oxidant. The optimized catalyst shows a selectivity of over 60% to glycolaldehyde, resulting in 1058 µmol gCat -1  h-1 production rate, and ≈3 times higher turnover number than NiOx -nanoparticle-decorated TiO2 photocatalyst. Diverse operando and in situ spectroscopies unveil the unique function of the Ni single atom, which can significantly promote oxygen adsorption, work as an electron sink, and accelerate the production of superoxide radicals, thereby improving the selectivity toward glycolaldehyde over other by-products.

Photocatalytic hydrogen production from biomass-derived compounds: a case study of citric acid.

Highly crystalline anatase TiO2 nanoparticles with high BET surface area have been synthesized by thermal hydrolysis of titanium(IV) bis(ammoniumlactato) dihydroxide aqueous solutions. The photocatalytic H2 production from aqueous citric acid (CA) solutions over Pt-loaded TiO2 has been investigated under different experimental conditions, that is, different CA concentration, temperature, light intensity, and pH of Pt/TiO2 suspension. For comparison, the photocatalytic dehydrogenation of triethanolamine (TEA) has also been investigated. The highest H2 production rates were obtained at pH 3 and 9 for CA and TEA, respectively. This behavior is readily explained by the adsorption characteristic of the employed reagent on the surface of the charged TiO2. The effect of the photocatalyst loading and the light intensity on the H2 production rate showed the same behavior in the case of CA and TEA evincing that these parameters are catalyst dependent. The apparent activation energies have been determined to be 13.5 ± 1.8 and 14.7 ± 1.6 kJ mol(-1) for CA and TEA, respectively, indicating the existence of an activation energy barrier in a photocatalytic process which can be attributed to the desorption of adsorbed products.